Data stream mirroring provides a duplication of a stream of data packets to an alternate destination in addition to a primary destination. Mirroring may be employed for debugging and diagnoses of network traffic anomalies, security and surveillance, and as a failover or redundancy path for critical data. Mirroring involves identification of a source stream, typically designated as a router port and optionally with filtering to restrict particular source or destination addresses, for example. The mirroring setup also designates a mirroring destination as the recipient of the mirrored stream, resulting in a duplicate packet for each packet in the identified source stream.